This is not the fault of the printer but the fault of word.
The way I did it successfully was as follow:
File > Page Setup > Layout = Landscape (sounds like you have already done this)
In the print dialoge, instead of OK, click Properties. On the layout tab, select landscape and below that select pages per sheet = 4 and then click ok... Then click OK to print.

is it possible that you have selected 2 sided printing in the printer or page setup? That is what it sounds like to me. When you say it does it in landscape, do you mean it only does every other page when printing in landscape mode? or do you mean it prints one in portrait and the next in landscape and so on?